Composite components may be manufactured using moulding processes using a mould to form a component during a forming process, in which heat and pressure are typically applied. The mould provides a surface which forms a component surface having a complementary shape to the mould surface. Intensification tools (“intensifiers”) are sometimes used in carbon fibre reinforced plastic component manufacture. Intensifiers enable the surface of the component which is not in contact with the mould tool to be moulded with greater precision. Intensifiers also assist in reducing the bulk volume of the component during the forming process. This debulking removes air from the material to help avoid undesirable voids in the final component. The intensifiers typically rely on the thermal expansion of the intensifier material during the forming process to apply pressure to the component. Therefore, intensifiers are often made from materials (such as aluminium) with coefficients of thermal expansion which are high relative to the coefficients of expansion of the component. Alternatively or additionally, an autoclave will typically be used to apply pressure during the forming process.
It is known to use intensifiers to control internal component dimensions for components manufactured using the VAP (Vacuum Assisted Process) system developed by EADS Military Air Systems, Augsburg. The tooling comprises a mould tool and an intensifier, where the intensifier is manufactured from a material with a higher coefficient of thermal expansion than the mould. The VAP process does not rely on an autoclave for pressure so component consolidation is achieved by allowing the intensifier to expand in all dimensions inside the mould and compress the component.
It is also known to use intensification tools in a process known as the RTI (Resin Transfer Injection) process. The intensifiers are manufactured from an airpad bag, which is constructed from carbon fibre and silicone. The carbon fibre helps to retain the tool's shape whilst the silicone expands to consolidate the component. The intensifier expands evenly in all directions.
The applicants have recognised that processes using intensifiers with a high coefficient of thermal expansion in three dimensions suffer from problems when used for long components. For example, as a result of the intensifier having a high thermal expansion coefficient (as is required to cause sufficient compression of the component-forming material), the intensifier expands lengthwise by an amount that makes it difficult to form accurately local changes in geometry in the component at the desired locations in the lengthwise direction.